Enhanced J
 c’s of YBa2Cu3O7−x–Ag ex situ annealed coevaporated films on LaAlO3 (100) substrates

Clausen, Thomas; Ejrnæs, M.; Olesen, M.; Hilger, K.; Skov, J. L.; Bodin, P.; Kühle, A.; Chorkendorff, Ib

doi:10.1063/1.113038

Cited by 6 publications

(6 citation statements)

References 6 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12] Although the intragranular critical current densities, J c approach the intrinsic values, the intergranular weak links still limit the current carrying capacity. 2,5,[13][14][15][16][17][18] Microstructure and granularity problems are the key issues of great interest.…”

Section: ͓S0003-6951͑97͒03022-2͔mentioning

confidence: 99%

Enhanced Jc and improved grain-boundary properties in Ag-doped YBa2Cu3O7−δ films

Selvam

Seibt²,

Kumar

et al. 1997

Applied Physics Letters

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A large increase (∼8×) in critical current density, Jc, was achieved for in situ laser ablated YBa2Cu3O7−δ–Ag films. High-resolution Auger electron spectroscopic investigation indicates that the Ag-doped films are stoichiometric with a relatively low grain-boundary extension (8 nm) in contrast to undoped YBa2Cu3O7−δ films (32 nm). Further analysis suggests that the doped film contains a much lower silver content (<0.15 wt %) than in the target material (5 wt %). These observations are in excellent agreement with the temperature dependence of Jc, the room-temperature resistivity, and the surface resistance results. Thus, Jc enhancement in Ag-doped films can be attributed to their superior properties, viz., improved microstructure characteristics and the reduced resistive grain boundaries.

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Section: ͓S0003-6951͑97͒03022-2͔mentioning

confidence: 99%

Enhanced Jc and improved grain-boundary properties in Ag-doped YBa2Cu3O7−δ films

Selvam

Seibt²,

Kumar

et al. 1997

Applied Physics Letters

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“…9 Doping of YBCO have been studied intensively ever since the discovery of the high T c 1-2-3 YBCO compound. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] For instance, by doping YBCO with Ag or Au both T c and J c can be enhanced depending on the growth parameters. The incorporation of Ag into YBCO has been postulated to give several effects; ͑i͒ improved values of J c due to intergranular diffusion of Ag resulting in reduced contact resistance between the superconducting grains, 11,15,17,19 ͑ii͒ a larger amount of the YBCO film is c-axis oriented 13,21 also resulting in improved values of J c and ͑iii͒ if the annealing temperature exceeds the melting point of the Ag/YBCOphase, the Ag atoms can diffuse into the YBCO lattice and substitute Cu atoms at the Cu͑1͒ sites.…”

Section: Introductionmentioning

confidence: 99%

“…6,7,23,26 This behavior has been explained by a decreasing density of 1-2-4 stacking faults with increasing film thickness assuming that the stacking faults act as core type flux pinning centers. 26 In this paper, we show that the 1-2-4 phases more likely make an additional contribution to J c below 80 K and we report on a novel technique that circumvents the problem on decreasing J c with increasing film thickness.…”

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confidence: 99%

Improved current transport properties of post annealed Y1Ba2Cu3O7−x thin films using Ag doping

Clausen

Skov

Jacobsen

et al. 1996

Journal of Applied Physics

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The influence of Ag doping on the transport properties of Y 1 Ba 2 Cu 3 O 7Ϫx thin films prepared by Y, BaF 2 , and Cu co-evaporation and optimized ex situ post annealing has been investigated. Both undoped and Ag doped films have values of T c above 90 K, but J c ͑77 K͒ is highly dependent on the nominal thickness ͑t nom ͒ of the as-deposited film. For undoped films with t nom р300 nm J c ͑77 K͒ ͑ӷ10 6 A/cm 2 ͒ decreases monotonically with increasing film thickness. Above 300 nm J c ͑77 K͒ decreases rapidly to values below 5ϫ10 5 A/cm 2 . Ag doped films with t nom у200 nm have higher J c ͑77 K͒ values than those of undoped films. Ag doped films have a maximum in J c ͑77 K͒ around 250 nm. As for the undoped films, there is a large decrease in J c ͑77 K͒ for Ag doped films with t nom у300 nm. It was found that the higher values of J c ͑77 K͒ for the Ag doped films were due to a better epitaxial growth of the YBCO compound. The low values of J c ͑77 K͒ for both undoped and Ag doped single layer films with t nom у300 nm were found to be due to the absence of 1-2-4 inclusions in these films. Based on these findings high J c ͑77 K͒ films with t nom Ͼ300 nm were grown by successive deposition and annealing of films with t nom Ͻ300 nm on top of each other. A 2ϫ150 nm undoped film was found to have a J c ͑77 K͒ value of 4, 1ϫ10 6 A/cm 2 . This is almost a doubling of the J c ͑77 K͒ value as compared to the value for the 300 nm single layer undoped film ͑2,2ϫ10 6 A/cm 2 ͒. Ag doped double layer films of 2ϫ150 nm and 2ϫ215 nm had comparable J c ͑77 K͒ values ͑5,8ϫ10 6 and 5,6ϫ10 6 A/cm 2 , respectively͒. In comparison with the undoped 2ϫ150 nm film J c ͑77 K͒ is thus further increased ͑by about 50%͒ when doping with Ag.

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“…In the case of cuprate superconductors, the films grown by pulsed laser deposition (PLD) from Ag-superconductor composite targets show an improvement in microstructure and an enhancement in critical current density (J C ). [2][3][4][6][7][8][9] Some of the reports show an optimum value of Ag in the target is essential to achieve the best results. 2,9 Amid the improvement in microstructure and other physical properties in these films, the final film always contained some amount of Ag.…”

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confidence: 99%

“…There are many reports in the literature about the versatile nature of silver (Ag) in modifying the microstructure of ceramic oxide materials and thereby instituting beneficial improvements in their microstructure and other properties in cuprate superconductors, [1][2][3][4][5][6][7][8][9] dielectric materials, 10,11 etc. In the case of cuprate superconductors, the films grown by pulsed laser deposition (PLD) from Ag-superconductor composite targets show an improvement in microstructure and an enhancement in critical current density (J C ).…”

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confidence: 99%

Silver-assisted growth of NdBa2Cu3O7−δ thin films: An approach for the growth of superior quality ceramic oxide films

Kurian

Sato

Makimōto

et al. 2005

Applied Physics Letters

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We have grown NdBa 2 Cu 3 O 7-δ films under silver atomic flux by molecular beam epitaxy, which show a drastic improvement in microstructure and also crystallinity leading to 30 % enhancement in critical current density. The most remarkable point is that the final film is free from silver. The key to our process in achieving a silver-free film was the use of RF-activated oxygen that oxidizes silver, nonvolatile, to silver oxide, volatile at the deposition temperature. This process enables one to utilize the beneficial effects of silver in the growth of oxide films and at the same time ensures that the final film be free from silver, which is important for high-frequency applications. This method can be made use in the growth of thin films of other complex oxide materials. a) Present address: TU Darmstadt,

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Enhanced J c’s of YBa2Cu3O7−x–Ag ex situ annealed coevaporated films on LaAlO3 (100) substrates

Cited by 6 publications

References 6 publications

Enhanced Jc and improved grain-boundary properties in Ag-doped YBa2Cu3O7−δ films

Enhanced Jc and improved grain-boundary properties in Ag-doped YBa2Cu3O7−δ films

Improved current transport properties of post annealed Y1Ba2Cu3O7−x thin films using Ag doping

Silver-assisted growth of NdBa2Cu3O7−δ thin films: An approach for the growth of superior quality ceramic oxide films

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